/*
 * SaleDAO.java
 *
 * Created on February 18, 2007, 8:31 PM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package edu.byu.isys413.samlam;

import java.sql.*;
import java.util.LinkedList;
import java.util.List;

/**
 *
 * @author Brian
 */
public class SaleDAO extends RevenueSourceDAO{
    ///////////////////////////////////////
    ///   Singleton pattern
    
    private static SaleDAO instance;
    
    /** Creates a new instance of SaleDAO */
    private SaleDAO() {
    }

    
    
    public static synchronized SaleDAO getInstance() {
        if (instance == null) {
            instance = new SaleDAO();
        }
        return instance;
    }
    
    /////////////////////////////////
    ///   CREATE
    
    /**
     * There's no need for two creates because we don't need
     * a connection to create BOs.  We run the insert statement
     * later, when it get's saved for the first time.
     */
    public Sale create() {
        Sale s = null;
        try{
            String id = GUID.generate();
            s = new Sale(id);
            Cache cache = Cache.getInstance();
            cache.put(s.getId(), s);
            
        }catch(Exception e){
            e.printStackTrace();
        }
        return (Sale)s;
    }
    
    
    /////////////////////////////////////
    ///   READ
    
    /**
     * This is the public read statement.  It loads an existing record
     * from the database.
     */
    public synchronized Sale read(String id) throws DataException {
        // check to see if id in the cache
        Sale s = (Sale)Cache.getInstance().get(id);
        if(s != null){
            // if so, return it immediately
            return s;
        }
        
        
        
        Connection conn = null;
        try {
            // retrieve a database connection from the pool
            conn = ConnectionPool.getInstance().get();
            // call read with a connection (the other read method in this class)
            s = SaleDAO.getInstance().read(id, conn);
            
            // release the connection
            conn.commit();
            ConnectionPool.getInstance().release(conn);
            
        }catch (ConnectionPoolException e4){
            throw new DataException("Could not get a connection to the database.");
            
        }catch (SQLException e) {
            // rollback
            try{
                conn.rollback();
                ConnectionPool.getInstance().release(conn);
            }catch(SQLException e2){
                throw new DataException("Big error: could not even release the connection", e2);
            }catch (ConnectionPoolException e3){
                throw new DataException("Could not get a connection to the database.");
                
            }
            throw new DataException("Could not retrieve record for id=" + id, e);
        }
        
        // return object
        return s;
    }
    
    /**
     *  This is a package method that is called by the public read (above) or
     *  by another DAO.  Either way we already have a connection to the database
     *  to use.  The user (controller) code never calls this one directly, since
     *  it can't know about Connection objects or SQLExceptions.
     */
    synchronized Sale read(String id, Connection conn) throws SQLException, DataException {
        // check again if the id is in the cache, and if so,
        // just get it from the cache.  we need to check again
        // because this method might be called directly from
        // another DAO rather than from read above.
        Sale sale = (Sale)Cache.getInstance().get(id);
        if(sale != null){
            return sale;
        }
        // if not in the cache, get a result set from
        // a SELECT * FROM table WHERE id=guid
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery("SELECT * FROM sale WHERE saleID = '"+ id + "'");
        
        //create a prepared statement
        //query the database
        //call sets from the result set
        Sale s;
        String memberId=null;
        if (rs.next()) {
            s = new Sale(rs.getString("customer_id"));
            
            s.setQuantity(rs.getInt("Qwuantity"));
            
            // get any subobjects (for example, if this was the SaleDAO,
            // we'd need to call the MembershipDAO to load the membership record.
            //if(s.getMember()==null){
            //    Member m = MemberDAO.getInstance().readByCustomer(s.getId(), conn);
            //    s.setMember(m);
            //}
            
            s.setObjectAlreadyInDB(true);
            
            
            // save to the cache
            
            Cache.getInstance().put(s.getId(), s);
            stmt.close();
        }else{
            throw new DataException("Object was not found in the database.");
            
        }
        // return the BO
        return s;
    }
    
    //////////////////////////////////
    ///   UPDATE
    
    /**
     * This is the public save method.  It is what is called when
     * the user (controller) code wants to save or update an object
     * into the database.
     */
    public synchronized void save(Sale sale) throws DataException {
        Connection conn = null;
        try {
            // retrieve a database connection from the pool
            conn = ConnectionPool.getInstance().get();
            // call save with a connection (the other save method in this class)
            this.save(sale, conn);
            // release the connection
            conn.commit();
            ConnectionPool.getInstance().release(conn);
        }catch (ConnectionPoolException e4){
            throw new DataException("Could not get a connection to the database.");
        }catch (SQLException e) {
            // rollback
            try {
                conn.rollback();
                ConnectionPool.getInstance().release(conn);
            }catch (ConnectionPoolException e4){
                throw new DataException("Could not get a connection to the database.");
            }catch (SQLException e2) {
                throw new DataException("Big error: could not even release the connection", e2);
            }
            
            throw new DataException("Could not retrieve record for id=" + sale.getId(), e);
        }
    }
    
    
    /**
     *  This is a package method that is called by the public save (above) or
     *  by another DAO.  Either way we already have a connection to the database
     *  to use.  The user (controller) code never calls this one directly, since
     *  it can't know about Connection objects or SQLExceptions.
     *
     *  By having other DAOs call this save method (rather than update or
     *  insert below, each DAO in a chained save (like the SaleDAO calling
     *  MembershipDAO calling InterestDAO save chain) can independently decide
     *  whether to udpate or insert the BO it's saving.  That's why I made
     *  update and insert private rather than package level -- if you call
     *  them directly from another DAO, this DAO can't decide whether it's
     *  object needs to be inserted or updated.
     */
    synchronized void save(Sale sale, Connection conn) throws SQLException, DataException {
        // check the dirty flag in the object.  if it is dirty,
        // run update or insert
        if (sale.isDirty()) {
            
            if (sale.isObjectAlreadyInDB() == true) {
                update(sale, conn);
            }else{
                insert(sale, conn);
            }
            // set the dirty flag to false now that we've saved it
            sale.setDirty(false);
            
        }
        
        // call save(bo, conn) on any subobjects (like SaleDAO to MembershipDAO)
  //      if(sale.getMember() != null){
  //          MemberDAO.getInstance().save(sale.getMember(), conn);
  //      }
        // touch the cache for the object
        Cache.getInstance().touch(sale.getId());
    }
    
    /**
     * This method is really a part of save(bo, conn) above.  It could be
     * embedded directly in it, but I've separated it into it's own method
     * to isolate the SQL udpate statement and make it more readable.  But
     * logically, it's really just a part of save.
     */
    private synchronized void update(Sale sale, Connection conn) throws SQLException, DataException {
        // do the update statement
        Statement stmt = conn.createStatement();
        stmt.executeUpdate("UPDATE Sale set saleID ='"+sale.getId()+"', quantity='"+sale.getQuantity()+"', productID ='"+sale.getProductID()+"' WHERE saleID='"+sale.getId()+"'");
        stmt.close();
    }
    
    /**
     * This method is really a part of save(bo, conn) above.  It could be
     * embedded directly in it, but I've separated it into it's own method
     * to isolate the SQL insert statement and make it more readable.  But
     * logically, it's really just a part of save.
     */
    private synchronized void insert(Sale sale, Connection conn) throws SQLException, DataException {
        // do the insert SQL statement
        Statement stmt = conn.createStatement();
        stmt.executeUpdate("INSERT INTO sale VALUES ('"+sale.getId()+"', '"+sale.getQuantity()+"', '"+sale.getProductID()+"')");
        stmt.close();
        // tell the object that it's now in the db (so we call update next time not insert)
        sale.setObjectAlreadyInDB(true);
    }
    
    
    ////////////////////////////////////
    ///   DELETE
    // we are not supporting because we never want to delete the sale from
    // our database.
    
}
